Apparatus for cracking oil



Nov. 2 1926.

G, l.. PRlcHARD APPARATUS FOR CRACKING OIL vOriginal Filedflune 22,,1915 2 sneets4s'nger1- nu ,0 Irma F \N\ NN IMWZUDZOU Nov. Z 1926. 41,605,063

G. L. PRlcHARD -APPARATUS FOR CRACKING OIL Original Filed June 22, 19152 sheets-Sheet 2 Iman/coc @LE-Mami fgt/W67@ Patented Nov. 2, 1926.

'NITED. STATES PTENT OFFICE.

GEORG PRICHARD, OF PORT'RTHUR, TEXAS, ASSIGNOR TO GULF REFINING CM-IPANY, F PITTpSnBUBG-H, PENNSYLVANIA A CORPORATION 0F TEXAS.

*APPARATUS ron Genome oIL.

Drignal application filed June 22, 1915, Serial No. 35,617. Divided andthis application led November i 20, 1920, Serial No. 425,450.Renewed'September 18, 1926.

This invention relates to apparatus forl cracking oil and it comprisesan advantageously vertical still body, agitating and scraping meanstherein, a shaft for operatlchamber; and it further comprises as a newapparatus a-still adapted to contain a body of oil, meansfor heatingsuch' still to a high temperature, means for removing vapors therefrom,means for continuously feeding oil thereto, means for maintaining apressure in the still, a stirrer mechanism adapted to keep granularcarbon in suspension in the oil in the still, and to scrape the heatedzone of the still, :such stirring mechanism includin@ a shaft adapted toreceive power, journa ing Imeans on the still -for the reception of theshaft and fluid cooled cooling and sealing means inclosing suchjournalmeans; all as more fully hereinafter set forth and as claimed.

y When heavy petroleum oils, such. as gas oils, petroleum residua, etc.are heated to a high temperature say above 600 or 650 F., they breakdown with production of lighter oils, such as kerosene or gasoline; thisbeing the Well known cracking process. tion is facilitated by operatingunder pressure. The elects of pressure upon the nature of the reactionsare not well understood; it has apparently other actions than f that ofmerely raising the boiling point of the oil. Cracking has been performedin many types of apparatus but on a practical scale mainly inunobstructed stills externally L heated. lnv the cracking operation,aside from the formation of the lighter products stated, there is alwaysa deposition of carbon and this carbon is in a hard, flinty form. ltdeposits on the heated'portion of the still as a coherent, denseincrustation and not only is its deposition a source of graveinconvenience and expense, since it is hard to` remove from the heatedportion of the still and causes that portion of the still to burnVthrough, but it also impedes the operation by impedng the supply ofheat. l have found that it also exercises another action; that itspresence has a marked influence upon the progress of 'the invention.rlFhis carment which is hotter than the body of oil,

The acbon has a catalytic influence in causing the deposition of morecarbon, and it may easily be perceived from the fact that newlydepositing carbonvinvariably forms onpreviously deposited carboni Thecarbon layer cohering to the heating element steadily' builds up, newlyformed carbon cohering to that already in existence. The net result is ahard dense layer lcovering the heating element, and where this heatingelement is the bottom of the still the still bottom fills up and theplates areapt to buckle and warp.

ln the ordinary operation therefore, considering a body of oil undercracking distillation in a steel or iron still heated from the bottom,it will be seen that the oil in the bot"- tom layer is subjected todifferent inuences from that in the top layer inthat the oil in thebottom layer is not only subjected to more heat, since it is next theheating elebut it is in contact with carbonA which is exercising lacatalytic effect. The top of the oil body, on the other hand, iscracking under a more uniform and lower heat and substantially in theabsence of carbon. Carbon does not appear to form to any great extentsave next the heating element, that is, next iron, or next previouslyformed carbon.

l have found that in cracking oils l can. produce very much more uniformresults and at the same time attain considerable economies in operationby providing stirring mechanism in the lstill adapted to produce aconstant dissemination of granular carbon or coke through the body ofoil. ln so doing not only does the stirring keep the temperature of theoil body much more uniform but lt nd that the coke tends to form insmall granules which do not adhere to thev heating elements to such anextent as is 95 usual. By keeping these coke granules separa-te and, asfar as possible, uniformly distributed throughout the body of. oil, thenewly formed carbon orcoke tends to deposit on that already inexistence; that is, it deposits on the granules or forms new granules.rlhese granules being in every portion of the oil body, the crackingoperation goes on much more uniformly and rapidly than is usually thecase. Substantially li may say l am performing my cracking throughoutthe entire body of the oil, instead of, very largely, in the layersimmediately in contact wlth the y heating elements. The stirring keepsall the .full of catalytically acting carbon.

oiluniform in temperature; i. e., the whole body of oil is at the highcracking temperature instead of, mainly, the layer of oil next theheating elements. And it is maintained With the opportunity for thedeposition of the excess carbon formed by the presence of thecatalytically acting coke granules, there is a greater tendency towardthe production of saturated gasoline; something whichis highlydesirable. p

It is however substantially impossible to luse a stirring mechanism ofany kind in the ordinary type of stills and particularly when the stillis run under pressure. 'Ihe walls of a still must be vapor-tight whileat the same time the temperatures of oil distillation in the crackingoperation are very high. It is ditlicult to furnish a tight gland or ajournal for rotating power-driven elements of a stirrer which shall beboth vapor-tight and uniform in engagement at all temperatures. Asstated, .a cracking still is ordinarily run at temperatures in excess of(500 F. These difficulties are accentuated when the still is run underpressure; say, a pressure of 80 pounds to 300 pounds. p

I have however found that by a particular structure of the top of thestill, I can maintain t'he portion of the still body carrying thejournaling means and the journaling v means themselves at a lower andmore convenient temperature than that prevailing in the body of thestill. And with these means I can produce a j ournaling of the shaftwhich will be tight against liquid 'and vapor and which is not affectedby the temperature of the still; in which the journalbearing has aboutthe same engagement with'the shaft whatever the temperature of the stilland of the liquid which the shaft-carriedmeans isr agitating. y

In the accompanyin illustration I have shown, more or lessiagrammatically, an embodiment of mylinvention. In this structure Fig. 1is a view, partly in elevation and partly in vertical section, of astill under this invention;

Fig. 2 is a detailed view on an enlarged scale ofthe still and stirringmeans; and Fig. 3 is a diagrammatical showing of a chain stirrer.

In this showing element 1 is va still of cy lindrical or other shape andmade of any suitable material, .suchfas steel boiler plate. It may beprovided with external or bottom firing means 2 of any suitable type.Art its top it is provided with vapor -outlet 3 leading to an air cooledchamber 4. Froml this chamber vapor line 5 passes to another air cooledchamber 6 beyond which is outlet 7 provided with loaded valve 8. Conduit9 takes the vapors to diagrammatically shown a valve 11 which may beused to cause stillY pressure to prevail throughout the condenser.Conduit 12 leads into( release cham- 'ber 13 provided with gage glasses14-and valved gas pipe 15. This gas release pipe may lead to anysuitable means for utilizing the gas (not shown). Liquid is removed fromthis tank through valve draw-ofi' 16. The air cooled condensing chambersare provided with runback 417 connnunicating with both and leading backinto the still.

The bottom 18 of the still may be, as shown, somewhat dished. Across thestill4 at adistance from the bottom is an angle iron bracket 19supporting a thrust collar, 20. rlhrough this thrust collar passesVertical shaft 21 carrying cross bars 22 to which may be connectedchains 23 (see Fig. 3) adapted to sweep the bottom orheated zone of thestill. On the top of the still is .plate 24 forming the support for thecooled bearing. On this plate is mounted casing 25. Elements 24 and 25may be a sin le casing. This casing is provided with in et 26 forcooling fluid and outlet 27. This outlet passes to cooling coil 28inchamber 29 which may contain water or the like and thence to pump 30which returns cooled fluid to the stated casingp/At its top this casingis provided with cover plate 31. As shown, this cover plate is securedin position by bolts and is gasketed to make it removable; but it may beriveted into place. Within the casing is bearin 32 through which theshaft passes. Meta licl packing 33 held yin place by element 34 .isprovided forming a stung box.; rlhe coverv plate carries another bearing35 also having a good packing around the shaft forming a secondY stunbox spaced from the first stuliing box. t the bottom the still isprovided with a draw-01E 37 for tar and granular coke. y Valve 38mounted on rod 39 serves to control discharge of tar to the exit 40.rllhe valve rod passes through tubular casing 41 having a screw stungbox 42 and is operated by lever 43. Motion is given the stirringmechanism by gears 44 from shaft 45. Cage 46 may be provided. 'Gutlet 47(see Fig. 1) may be provided leading to a safety valve (not shown).rllhe still may be charged either continuously or from time to vtimethrough charging line 48. f

In the use of this structure, the still is charged to any desired heightwith the oil to be cracked or distilled, such as gas oil, pe-f troleumresiduum, heavy crude oils, etc. Or a charge of ordinary crude may beplaced in the still and distilled until the lighter oils are distilled.If the pressure of the still is not desired in the condenser, valve 8may loe used and valve 11 left open; but if it is desired that the stillpressure extend through while operating the stirrer. A,If desired, the`lpounds to bemost advantageous.

the condenser, valve 11 may be, closed to an appropriate degree andvalve 8 kept open. In, either event heating is continued until gage 46shows the desired amount of pressure within the still. During thisheating the stirrer-is kept in steady movement over the heated zone,scraping the carbon from the heated zone as it develops. When carbon beins to' develop, instead of baking on and ad ering to theheating'elements, it is removed and Aforms loose granular material whichis kept circulating through the body of oil. When the desired amount ofpressure is attained, valve 8 or 'valve 11 may be openedl to the desiredextent and distillation under pressure begun. The pressure is kept atthe desired oint byadjustment of the ring means an of the reducing valveused. While I may use from 80 to 300 pounds pressure, I have found apressure of about 95 During this heating operation oil is kept flowinginto the casing 25 through inlet 26 and is dis-y charged through outlet27 This iow of oil keeps the whole bearing at a comparatively lowtemperature irrespectiveof the heat in the still. The influence ofexpansion being removed, a tight joint can be maintained oilmay beintroduced through 26 at a pressure equivalent to that prevailing in thestill.-

If the oil is the same character as that under distillation, it may bemaintained at a somewhat higher' pressuregso as to make leakage inward.`Inany event, because of the doublebearing means 32 and 35, leakage isnot to Y' be feared.

The stirrer may advantageously be keptV be kept at any temperaturedesired.

When the distillation has gone to the desired extent, lever 43 may belifted, Withdrawing plug 38 and allowing the tar and v cokey c bon inthe'still to go to exit through 37. The operation of this still may beconf tinuous, discontinuous and semi-continuous. Where it is desired tointroduce oil throughout the distillation this may be done through theinlet 48, See Fig. 1

When the chain is ,used as is shown in Fig. 3 it shouldadvantageously'be arranged to sweep the heated zone of the still andassist the stirrer in loosening any Yadhering carbon.

This application is a division of myprior wharrcnimis: a l l. Anapparatus for treating oil under pressure comprising a still, a movablestirrer therein, an actuating shaft extending outside of the still,aehousingchamber surrounding` the shaft at its point of exit from thestill, spaced stufling boxes on the shaft, one .such stufng box being`located. in the housing chamber and the other outsidelthereof, and

means for maintaining cooled fluid under l pressurel in the housingchamber and around the stuffing box located therein.

2. An apparatus for treating oil under pressure comprising a still, amovable stirrer.

therein, an actuating shaft extending outhousing chamber and the otherbeing located outside thereof, and means l`for circulating cooled loilthrough the housingchamber and around the stufling box therein and formaintaining a fluid pressure in the housing chamber equal to or greaterthan that existing within the still. I

3. An apparatus for cracking oil compris- 4ing a still, heating meansfor a portion thereof, stirring means operating in proximity to theheated portion of the still to remove deposited carbon therefrom and tokeep it in suspension in the oil in the still, a shaft for operatingsaid stirring means, a stuffing box fdr said shaft, a chambersurrounding said stulling box, means for circulating oil through saidchamber and around said stuffing box, and another stuiingbox for theshaft outside of said chamber, Vtogether with means for operating saidshaft. i 4. In an oil still adapted 'to work under high pressure, astill body havingA a topro tary stirring-mechanism within the still, a

noA l shaft for operating said mechanism passing through said=top, abearing for said shaft on saidc top, a, closed housing surrounding saidbearing, a bearing for the housing through which the said lshaftextends, means for rotating the shaft, and means for .cir-

culating a cooling fluid through said hous ing and around the stuflingbox therein. A 5. In an`oil' still adaptedto Work under high pressure, avertical casing, a stirring` device mounted to sweep the'bottom of thecasing, a shaft f\or said device, a cross-bar and thrust collar holdingsaid shaft at a point above the bottom, a top for the casing,`

4 ,fixedmy signature. j

application Serial No. 35,617, filed June 22,

GEORGE L. PRICHARD.

